Bats Pest Note

Information on bats can also be seen on the Healthy Canadians website.

Bats - What are they

Bats are flying creatures of the night, not much bigger than a house mouse. Bats can live up to 10 years. The wingspan of the two most common Canadian species, the little brown bat and the big brown bat, ranges from 20 to 35 cm (8 to 14 inches) although some can be larger. Bats will mate in fall or winter and the pups are usually weaned in July or August.

Sometimes in favourable winter weather conditions, such as high humidity and temperatures above freezing, bats will roost in buildings throughout the winter. Bats emit a high-frequency sound inaudible to humans. These sounds bounce off objects in their paths enabling them to avoid obstacles and detect flying insects. Sometimes bats can be seen around outdoor lights which have attracted insects. To save energy, bats have the ability to enter a dormant state which makes them appear to be sick, asleep or dead. They may also bare their teeth and squeak loudly, leading many people to believe they are vicious. In reality, the bat is only trying to ward off a possible attack from one of their predators which include hawks, falcons, owls, cats, snakes, and humans.

Bats are usually detected by their droppings or noise-making. Their musty smelling droppings can be mistaken for that of mice or birds. Bat droppings can look like crushed fine, shiny undigested insect parts, while mouse droppings are firm and do not disintegrate readily. No white colour appears in bat feces as it does in bird feces.

In order to determine whether bats are roosting in a structure, inspect the exterior before dark when bats leave their roosts, or when they return from their night escapade at dawn. An hour's observation should be sufficient to identify possible entry and exit ways.

Because bats are nocturnal creatures, they will not leave their roosting sites if they are faced with bright light. Therefore, while inspecting the outside of a structure maintain a dim light by applying several layers of red cellophane over the head of a flashlight, secured with a rubber band.

What can they do?

A single brown bat is very beneficial in that it can easily capture 600 mosquitoes an hour while a colony of 500 bats can easily eat a million insects nightly. When bats invade dwelling structures, however, they become a nuisance. Their presence, ectoparasites, and the odour from their fecal matter and urine, are all of concern.

Rabies is a potentially fatal viral disease in humans and other mammals that is transmitted by bites or scratches and through contact with saliva or bodily tissues. Although attacks by rabid bats are rare, anyone bitten or scratched by a bat or any other wild animal should seek medical attention immediately. Cats and dogs stand the greatest chance of becoming infected by picking up a diseased animal as they use their mouths to do so. The best way to protect a pet from rabies is by regular vaccination.

Anyone who spends considerable time in attics, caves, or possible bat roost sites may consider getting immunized against rabies. Children should be taught not to handle any wild animal floundering on the ground or a pet behaving strangely. Bat exposure is considered to be very high risk as bat bites are very small and not easily seen. People exposed to a bat can get rabies even though no bat bite is noticed. If a bat is found in a room where someone was sleeping or where a young child may have been alone even for a few moments, it is advisable to take the precaution of seeking medical attention. The bat should also be captured for testing.

If you have been bitten by an animal and think you may have been exposed to rabies, you should immediately wash and flush the wound with soap and water. Seek attention from a health care professional as soon as possible to assess your risk and treatment options.

Dead bats found on the ground should be shovelled into a container and transported to public health authorities for autopsy.

Histoplasmosis is a fungal disease in humans that may be contracted through the inhalation of dusty bat manure. Most infections have no symptoms or appear as a mild respiratory illness. Bats are not the only source of this pathogen. It can be found in soil and bird droppings and is carried by the wind. A respirator and other protective clothing should be worn when working in bat roost sites.

How can I manage them?

It is easier to dislodge newly installed bat colonies than more established ones. When a bat infestation takes place in your home, consider a combination of methods. The best time to control bats is in the spring before they return to the roost, or in the fall when they leave for the season, to ensure that no young bats remain trapped inside the structure.

Stapling or duct-taping bird netting over entry points, with the bottom part hanging loosely at one to several inches from the building, will allow the bats to crawl under and exit the roost site, while returning bats will not be able to re-enter. Watch your house for several evenings at dusk to ensure bats have not found another way to get in. Once bats are no longer seen exiting the building, the netting can be removed and the holes sealed.

Since bats tend to avoid daylight, lighting an infested area may cause them to leave. This method is believed to be most effective if done shortly after bats return from their hibernating sites.

Bats help control mosquitoes, so should be encouraged to roost in our neighbourhoods (just not in our homes or buildings). One way to achieve this is to install bat houses in trees (east or southeast orientation, no obstruction from tree branches) where bats will not be a nuisance. Bat houses can be purchased in hardware stores and garden centres or easily built with rough leftover wood. If you have successfully removed bats from your home, the best way to keep them out is to seal all points of entry such as spaces under eaves, electrical conduits, and holes around the chimney and windows. Vents that must be kept open can be protected with a fine screen and larger openings can be sealed with a high quality caulk, sheet of metal, or window screen. Unlike rodents, bats will not gnaw their way through, but they will push aside loose barriers.

If a bat accidentally wanders into a house through a window, door, or unused chimney, open only the doors and windows that allow access to the outside and wait for the bat to follow the fresh air. Since bats usually rest during the day you may want to wait until nightfall when the bats will leave on their own. Just make sure the room is dark enough for the bat to realize that it is night.

If the first method is unsuccessful, consider capturing the bat and releasing it outdoors.

The bat can be netted or captured in a small box, can or tube from a roll of paper towel. Wear leather work gloves, place a container with breathing holes over the bat, and carefully slide a piece of cardboard under the container leaving no space for the bat to fly away. Remember these are fragile creatures that should be handled with care.

Products

No pesticides are registered in Canada for the control of bats.